Imagine that the Roman Polanski horror classic “Rosemary’s Baby” wasn’t adapted from a best-selling novel. Imagine someone just pitched it in a studio office as “young woman is impregnated with Satan’s baby and a coven of geriatric New Yorkers drive her to madness.” Imagine that person being shown the door and the movie being made for chump change and winding up the forgotten second half of a 1970 drive-in double-feature instead of the highly-regarded film it became. That could have happened.

It’s like this: the normal rules don’t apply in horror. Plots that seem outlandish — even flat out ridiculous — if properly executed, can turn audiences into terrified believers. Of course, it’s that whole “properly executed” part that seems to trip up the most filmmakers. That’s why its pretty easy to have extremely low hopes for this week’s horror release “Chain Letter,” about a killer who stalks teens who refuse to forward chain emails. That’s right, he’s taking vengeance on kids who dare to set up an adequate spam filter. Could it surprise everyone? Maybe. Will it? Unlikely.

But it gets dumber. And dumberer.

'One Missed Call,' 2008

Cell phones possessed by evil spirits call their victims in advance of their deaths. Then the victims die. No one thinks to change their number, get rid of the phone or simply send the death spirit to voice mail. At one point in the film an exorcism is performed on a phone. Ray Wise from “Twin Peaks” shows up, as does Margaret Cho. That’s when you think it’s maybe supposed to be funny. But no, she just plays a detective.

The fourth installment of any horror franchise is usually pretty bad. But more often than not, it’s because the filmmakers give you nothing new. This chapter of the Pinhead chronicles chooses, instead, to deliver a lot of crazy newness by zooming back and forth between a 22nd century spaceship and an 18th century French puzzle-master in a ruffly shirt, all in the service of the evil Rubik’s Cube that unleashes the needle-faced one. Sort of a wacky history lesson more than a horror film. Because you know what’s scary about French toymakers in puffy clothes? That’s correct, nothing. See also: “Leprechaun 4: In Space.”

'The Unborn,' 2009

The angry, restless spirit of a boy — one half of a set of twins — killed in the Holocaust during World War II, roams history waiting to be reborn. So it makes perfect sense that he’d select a hot teen girl of 2008 as the object of his wrath. There are murders, hallucinations, tornado-like exorcisms and a crazily over-acting Jane Alexander shouting about the Holocaust. Fun project: Find a fan of ludicrously bad movies and say “Jumby wants to be born now.” Watch their eyes light up. Then be prepared for them to blather on and on excitedly about it for a few minutes.

'Jack Frost,' 1997

Because Christmas is, if nothing else, a time when the world rejoices in the concepts of reincarnation and serial murder, it’s fitting that someone would eventually make a film about an obsessive killer who dies and is then brought back to life as a really unpleasant snowman bent on destruction. He dispatches his victims in appropriately holiday-themed ways with icicles and tree lights, but it takes a while before anyone thinks about the combat qualities of a standard household blow-dryer.

So you’re blind and they operate and give you some new eyeballs. That’s great. But what if those new eyes are supernatural and can see death coming? What if those ghost-corneas haunt your every waking moment with visions of people consumed by fire? What if they make you put your head in the oven for no reason? That would be a bummer and you’d be grateful to be blinded again. It’s the kind of “atmospheric” movie they think is scary in Japan but actually just makes no sense. But it was a big hit there and in some arthouse theaters stateside, so Hollywood jumped on it like it was “The Ring” and stuck Jessica Alba’s head in that oven. Upside: directed by a guy named Oxide. That’s a cool name.

'Evilspeak,' 1981

Clint Howard is a bullied social outcast who uses his satanic computer to get revenge on his classmates. You know the computer has the Devil in it because it flashes a glowing blood-red pentagram at him and inspires him to commit himself to the dark lord. Puppies are killed in the process. It’s part of a long and dorky tradition of horror movies that are really about the fear of a nascent technology (or whatever all the kids happen to be into at that moment in the culture). Speaking of which…

'Trick or Treat,' 1986

In the 1980s, “satanic panic” was all the rage, and an especially loopy strain of it existed in the form of preachers holding seminars on the perils of heavy metal, particularly if played backwards on turntables. Hence this story about a teenage metalhead (Marc Price, Skippy from “Family Ties”) whose favorite rock star dies in a mysterious fire. The only copy of his new, unreleased record, however, contains his spirit. When played backwards, the rocker helps his teen fan to get revenge on bullies. But when the evil rocker suggests murder, it’s up to our hero to smash any electronic equipment that would convey the message. Finally the mean music man is lured into a cassette tape and destroyed. Best (worst) of all, this one tried to have its devil’s-food cake and it eat it too by casting Gene Simmons and Ozzy Osbourne, two men whose acting talents are inversely proportional to their music-making skills.

This one never hit theaters; it was made for ABC Television. But its cult reveres it mostly because of its idiotic premise (and admittedly amazing title, complete with superfluous exclamation point). And what a Grade A idiot premise it is: a meteorite with strange powers lands on Earth. When a work crew tries to move it with a bulldozer, the heavy shoveling equipment is possessed by the alien boulder’s power and goes on a killing rampage. And then it just dissipates. Biggest disappointment: thanks to its TV movie status there was never a cool poster created to trumpet its arrival on the junk culture scrapheap.

'Happy Birthday to Me,' 1981

In the creative aftermath of “Black Christmas,” “Halloween,” and “Friday the 13th,” the 1980s turned into a muddy cesspool of slash-alike calendar-centric movies. “Graduation Day,” “My Bloody Valentine” and others painted by the numbers and sent a stream of murdered teen bodies down the multiplex conveyor belt. This one barely accomplished even that goal, loosely tying stalker-style murders around the birthday of “Little House on The Prairie” star Melissa Sue Anderson. In fact, it appears that the entire film’s reason to exist is to deliver the kabob-skewering-a-face murder depicted on the gruesome poster. Worse, they convinced aging screen legend Glenn Ford to be in it.

'Brainscan,' 1994

Edward Furlong loves interactive video games. And you know what that means: much like computers and heavy metal, they will eventually make you murder people. That happens a lot. Coming soon, if history is any indication, a movie featuring a haunted Twitter account. Upside: a '90s alt rock soundtrack with cool bands like Mudhoney and Tad that made it seem more like a teen movie than the worried parent bummer it really is.